A simple and sensitive device is presented based on the use of pencil-drawn paper based electrochemical detector placed at the end of a cotton thread fluidic channel in wall-jet configuration. This innovative and fast responding electroanalytical system can be adopted for both single and dual electrode electrochemical detection, this last achieved by applying two different potentials at two independent working electrodes drawn on the opposite faces of the paper based detector. Its performance was preliminarily optimized by adopting hexacyanoferrate(II) as probe species undergoing reversible electrochemical processes. These devices were then used for the single electrode detection of ascorbic acid in aqueous samples and the dual electrode detection of orthodiphenols in extra virgin olive oils (EVOOs). In fact, these devices enable hydrophilic orthodiphenols, typically present in EVOOs (extracted by a 80:20% v/v acetonitrile/water mixture), to be discriminated from hydrophilic monophenols instead present in almost all vegetable oils. Flow-injections runs were conducted by using a 0.01 M H2SO4 + 0.5 KCl running electrolyte allowing the rapid and selective detection of hydrophilic orthodiphenols with satisfactory sensitivity and a low enough detection limit (2 μM). Different real samples of EVOOs and sunflower oils were analyzed. Abundant enough contents of orthidiphenols were found in EVOO samples, while no trace of these antioxidants was found in sunflower oils.

中文翻译：

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一种带有壁喷射铅笔画纸的双电极检测器的棉线流体装置

提出了一种简单而灵敏的装置，该装置基于使用放置在壁射流配置的棉线流体通道末端的基于铅笔画纸的电化学检测器。这种创新和快速响应的电分析系统可用于单电极和双电极电化学检测，最后通过在纸基检测器相对面上绘制的两个独立工作电极上施加两个不同的电位来实现。通过采用六氰基铁酸盐（II）作为经历可逆电化学过程的探针物种，对其性能进行了初步优化。然后将这些设备用于单电极检测水性样品中的抗坏血酸和双电极检测特级初榨橄榄油 (EVOO) 中的邻二酚。实际上，这些装置能够将通常存在于 EVOO 中的亲水性邻二酚（通过 80:20% v/v 乙腈/水混合物提取）与亲水性单酚区分开来，而不是存在于几乎所有植物油中。流动注射运行是通过使用 0.01 M H2SO4 + 0.5 KCl 流动电解液进行的，允许以令人满意的灵敏度和足够低的检测限 (2 μM) 快速和选择性地检测亲水性邻二酚。对 EVOO 和葵花籽油的不同实际样品进行了分析。在 EVOO 样品中发现了足够含量的邻二酚，而在向日葵油中没有发现这些抗氧化剂的痕迹。流动注射运行是通过使用 0.01 M H2SO4 + 0.5 KCl 流动电解液进行的，允许以令人满意的灵敏度和足够低的检测限 (2 μM) 快速和选择性地检测亲水性邻二酚。对 EVOO 和葵花籽油的不同实际样品进行了分析。在 EVOO 样品中发现了足够含量的邻二酚，而在向日葵油中没有发现这些抗氧化剂的痕迹。流动注射运行是通过使用 0.01 M H2SO4 + 0.5 KCl 流动电解液进行的，允许以令人满意的灵敏度和足够低的检测限 (2 μM) 快速和选择性地检测亲水性邻二酚。对 EVOO 和葵花籽油的不同实际样品进行了分析。在 EVOO 样品中发现了足够含量的邻二酚，而在向日葵油中没有发现这些抗氧化剂的痕迹。